Apparatus for cracking hydrocarbons



J. W. COAST, JR. APPARATUS FOR CRACKING HYDROCARBONS.

APPLICATION FILED APR. 16, 1917. RENEWED JUNE 14, 1920.

1,348,268, Patented Aug. 3,1920.

2 SHEETSSHEET I.

L W. COAST, JR.

APPARATUS FOR CRACKING HYDROCARBONS.

APPLICATION FILED APR. 16. 1917. RENEWED JUNE 14, 1920.

1,348 268 Patented Aug. 3, 1920.

2 SHEETSSHEET 2.

(XV (draw;

UNITED STATES PATENT OFFICE.

JOHN W. COAST, JR., OF TULSA, OKLAHOMA, ASSIGNOR TO THE PROCESS COMPANY,A CORPORATION OF MARYLAND.

APPARATUS FOR CRACKING HYDROGARBONS,

Specification 01' Letters Patent.

Patented Aug. 3, 1920.

Application filed April 16, 1917, Serial No. 162,384. Renewed June14,1920. Serial No. 889,010.

To all whom it may concern Be it known that I, JOHN V. COAST, Jr., acitizen of the United States of America, a resident of Tulsa, in thecounty of Tulsa, State of Oklahoma, have invented certain .new anduseful Improvements in Apparatus for Cracking Hydrocarbons, of which thefollowing is a full, clear, and exact description, reference being hadto the accompanying drawings, forming a part of this specification.

My invention relates to lmpr'ovementsin apparatus for cracking highboiling point petroleum hydrocarbons. In cracking hydrocarbons of thiskind to obtain cracked gasolene it has been found necessary to condensethe unconverted, or partially converted, high boiling fractions beforethey reach the condenser from which the low b011- ing point product isrecovered. In actual practice, the vapor is usually conducted away fromthe still and then through one or more reflux condensers whereby thehigh boiling fractions are condensed, the condensate being conductedfrom the reflux condensers to the still for further treatment.

The main object of this invention is to condense the high boiling pointfractions 1n the upper portion of the still, perm tting the condensateto drop back into the liquid, and conducting the remaining vapor fromthe still to the condenser, from which the product is recovered. T oaccomplish this, the upper portion of the still 18 maintained in arelatively cool condition, the vapor being deflected and conducted alongthe cool portion of the still in such a manner that the temperature ofall of the vapor is very materially reduced. thereby condensing the highboiling point fractions before the vapor passes from the still. Owing tothe peculiar manner in which the vapor is baiiled, deflected, andbrought into contact with the cool parts of the still, the temperatureof the vapor may be reduced to such a low degree that only the desiredlow boiling point fractions will escape from the still. In this event,it will be unnecessary to pass the vapor through the ordinary refluxcondensers.

In the preferred form of the invention, a relatively cool fluid,preferably a high boiling point hydrocarbon liquid, is introduced intothe vapor confined in the still. This liquid serves as a condensingmedium for the vapor, and it is eventually vaporized and cracked in thestill. The vapor is also, preferably, subjected to the action ofrelatively cool steam before it escapes from the still.

Figure I is a diagrammatical view of a cracking apparatus constructed inaccordance with my invention.

Fig. I1 is an enlarged transverse section taken through the middleportion of the still, showing the baffles and the restricted vaporpassageways at the upper portion of the still.

Fig. III is an enlarged longitudinal section of the still.

To illustrate the invention, I have shown a cracking still 1, in theform of a large boiler, arranged above a heating chamber2, and connectedby means of a vapor pipe 3 to a water cooled condenser 4 from which thelow boiling point product is recovered.

The apparatus shown is particularly adapted for use in cracking highboiling point products of distillation, such, for example, as thedistillates or residues resulting from the distillation of crudepetroleum. The contents of the stillare, of course, maintained underpressure, and any desired pressure may be obtained by regulating a valvein the vapor pipe 3. The pressure in the still is preferably greaterthan 50 pounds per square inch, for example, about 80 pounds per squareinch, and the temperature of the liquid contents of the still preferablyranges from about 600 F. to about 800 F. The low boiling point vapor,passing from the liquid, flows through the relatively cool upper portionof the still and is discharged into the vapor pipe 3. The relativelyhigh boiling point fractions are condensed in the still, as will behereinafter described, and permitted to drop back into the liquid. Thishigh boiling point condensate includes some heavy coke-forming fractionscommingled with lighter fractions which may be redistilled to form apart of the low boiling point product.

The end portions of 'the still bottom are seated upon the walls 6 of theheating chamber 2. and these walls protect said end por- 'tions from theintense heat of the heating chamber. The heat is transmitted directlythrough the middle portion of the still bottom. and the protected endportions of said bottom are maintained in a relatively cool condition.

The vapor cooling meansincludes a large vapor passageway 8. End bafllemembers 9,

located at the'ends of the long'bafile member 7, are separated from theend walls of the still to form restricted passageways 10 or the risingvapor flowing t0 the restricted passageway 8.v The lower edges of theend baffle members 9r'are located slightly above the surface of theliquid in the still to form restricted outlet ports 11 for the vaporflowing to the end passageways 10. f

An air cooled tower 12 extends upwardly from the top wall of the stillto receive the I vapor flowing from the long restricted-passageway 8. 13designates a cylindrical 25 baffle. device arranged in the air cooledtower and separated from the upright wall thereof to provide avrestricted annular passageway 14 for the rising-vapor. The cylindricalbafile device 13 is in the form of a receptacle, open at the top toreceive the vapor and closed at the bottom to exclude the rising vapor.

To prevent the vapor 7 from escaping around the lower longitudinal edgesof the long baffle member 7, these edges are preferably located belowthe level of the liquid in the still, as shown most clearly in Fig. II.Condensate troughs 15, located adjacent to the longitudinal edges of thebaflie member 7, are inclined toward the ends of the still. Thecondensate, flowing from the baffle member 7, drops into the troughs 15,and the .heavy coke-forming fractions are thereby action "of relativelycool air currents. 55.

conducted to the end portions: of the still, Where they will settle uponthe still bottom at points above the walls 6. These heavy fractions dropby gravity, and they accumulate on the protected end portions of thestill; bottom, instead of being permitted to collect .at points wherethe heat is transmitted to the still.

Instead of being protected, the upper portion of the still is subjectedto the cooling A jacket"' '16, approximately semi-circular in 1 crosssection, is preferably arranged over the correspondingly shaped upperportion of the still to provide an air passageway 17, and air underpressure may be discharged from a pipe 18 to thepassageway 17'for thepurpose of'creating a forced draft of cool air over the top wall of thestill. A perforated discharge pipe 19, located in the restrictedpassageway 8. is connected to a supply pipe 20 through which arelatively cool fluid is conducted for the purpose of cooling the vapor.This relatively cool fluid is, preferably, a high boiling pointhydrocarbon liquid, and it is discharged through the numerousperforations inthe pipe 19 so as to cool the vapor, at the same timecooling the upper portion of the still. This hydrocarbon liquid, inaddition to serving as a cooling medium, is subjected to the crackingprocess carried on-in the still, and it eventually forms part of the lowboiling point product.

A perforated discharge member 22 (Fig. III) arranged in the cylindricalbaflie device 13, is connected to a steam pipe 23 provided with aregulating valve24. Relatively cool steam, passing from thedischargemember 22, is forced into the vapor in the cylindrical bafliedevice 13.

The vapor rising from the liquid under the long bafiie member 7 istrapped by the baffles 9. This vapor passes under the lower edges of theend baffles 9, upwardly through the restricted end passageways 10,through the long restricted passageway 8 above the baflie 7, thenceupwardly in the restricted passageway 1 1, downwardly in the cylindricalbafile device 13 and then into the vapor pipe 3. The upper portion ofthe still is maintained in a relatively cool condition, as previouslypointed out, and the vapor is baflled, deflected, brought into contactwith the cool parts of the still, andotherwise acted upon in such amanner that the temperature of all of the vapor is greatly reduced. As aconsequence, the high boiling point hydrocarbons are condensed in thestill, and all of the vapor escaping from the still maybe condensed inthe water cooled condenser 4 from which the cracked product isrecovered.

The condensate formed in the cylindrical baffle device 13 passes througha liquid seal 8, between the top wall of the still and the bafiie 7,flows downwardly on the top face of the a baflie 7 and commingles withthe liquid'in the still. The heavy coke-forming fractions are conducted,by the inclined troughs 15, to the end portions of the still, where theydrop by gravity to the protected end portions of the still bottom.

In treating petroleum hydrocarbons to obtain cracked gasolene, theobject is to recover all of the vaporized fractions having a normalboiling point lower than about 500 F The fractions having higher boilingpoints should be continually subjected to the high pressure and hightemperature in the still for the purpose of converting them into lighterfractions. By reducing the temperature of the vapor in the still asherein shown and described, all of the vaporized fractions having anormal end or dry point higher than 500 F. may be condensed in thestill. All of the vapor passing from the still will then be free fromthe undesirable heavy fractions, and the desired product may be obtainedby condensing all of this vapor in the water cooled condenser 4.

The condensing action at the upper por-.

tion of the still can be varied by regulating the flow of relativelycool steam, air or liquid, each of which serves as a cooling medium forthe vapor. It will, therefore, be apparent that the apparatus can beeasily adjusted or regulated to condense, or knock back all of thefractions having a boiling point higher than about 500 F.

- I claim 2- 1. A. cracking still having a vapor outlet, and "aporcooling means including a baflle device arranged within the still andextending from a point near one end of the still to a point near theopposite end, said bafile device being located near, and se pa-.

rated from, the top wall of the still to form a restricted passagewayfor the vapor flowing to said outlet, said baflle device being in theform of an inverted trough, closed at the top and open at the bottom toprovide a vapor trap, and the lower edges of said baflle device beinglocated below the liquid level in the still so as to prevent the vaporfrom flowing around said edges.

2. A cracking still having a vapor outlet, and vapor cooling meansincluding a baflie device arranged within the still and separated fromthe top wall thereof to form a restricted passageway for the vaporflowing to said outlet, and an end'bafl'le located at an end of saidbafile device and separated from an end wall of the still to formarestricted passageway for vapor flowing to the first mentionedpassageway, the lower edge of said end battle being located above andadjacent to the li uid level in the still.

3. A cracking still aving a vapor outlot, and vapor cooling meansincluding a battle (lCX'lCG arranged within the still and separated fromthe top wall thereof to form a restricted passageway for the vaporflowing to said outlet, and end battles located at the ends of saidbaflle device and separated from the end walls of the still to formrestricted passageways for the rising vapor flowing tothe firstmentioned passageway, the lower edges of said end bafiies being locatedabove and adjacent to the liquid level in the still.

4. A cracking still having a vapor outlet, and vapor coolingmeansincluding a vapor trap in the form of an inverted trough closed atthe top and open at the bottomand located within the upper portion ofthe still and separated from the walls thereof to form restrictedpassageways for the vapor flowing to said outlet.

5. cracking still having a vapor out let, and vapor cooling meansincluding a vapor tra'p in'the form of an inverted trough closed at thetop and open at the bottom and located within the upper portion of thestill and extending approximately from one end of the still to theother, said vapor trap being separated from the adjacent walls of thestill to form restricted passageways for the vapor flowing to saidoutlet.

6. A cracking still having a vapor outlet, and vapor cooling meansincluding a battle device arranged within the still and extending from apoint near one end of the still to a point near the. opposite end, saidbafile device being located near, and separated from, the top wall ofthe still to form a restricted passageway for the vapor flowing to saidoutlet, a discharge member arranged within the still between said bafiledevice and the top of the still, and means for conducting a relativelycool fluid into said discharge member.

7. A cracking still having a vapor outlet, vapor cooling means includinga battle device arranged within the still and extending from a pointnear one end of the still to a point near the opposite end, said baflledevice being located near, and separated from. the top wall of the stillto form a restricted passageway for the vapor flowing to said outlet,and troughs arranged in the still to receive the condensate flowing fromsaid baflie device.

8; A cracking still having a vapor outlet, vapor cooling means includinga bafile device arranged Within the still and ex tending from a pointnear one end of the still to a point near the opposite end, said bafiledevice being located near, and separated from, the top wall of the stillto form a restricted passageway for the "apor flowing to said outlet,and inclined troughs whereby condensate flowing from said baflie deviceis conducted to an end portion of the still, said troughs being locatedadjacent to the lower longitudinal edges of said baflle device.

9. A cracking still having a vapor outlet, and vapor cooling meansincluding a baflie device in the form of an inverted trough arrangedwithin the still and separated from the top wall thereof to form arestricted passageway for the vapor flowing to said outlet, and acooling tower arranged to receive the vapor flowing from said restrictedpassageway to said outlet.

In testimony that I claim the foregoing I hereunto aflix my signature.

JOHN W. COAST, JR.

